JP7581975B2 - Box column joint method - Google Patents

Description

The present invention relates to a method for joining box columns, in which the joint between the upper and lower column members that make up the box column is joined by welding.

To construct a box column, the joint between the upper column member and the lower column member is joined by automatic welding using a robot. In this automatic welding, it is known that a tab is placed at a 45-degree angle at the joint and two opposing sides are welded (pre-welded), and then the tab is removed and the remaining two sides are welded (post-welded) (see, for example, Patent Document 1). In the automatic welding method for box columns described in this document, a fire-resistant flux tab is placed diagonally in the groove fillet of the upper and lower opposing box columns and welding is performed.

Japanese Unexamined Patent Publication No. 54-103754

As mentioned above, by placing the tabs diagonally and welding them, the shape of the end can be adjusted. However, internal or surface defects may occur at both ends, at the start and end points of the previous weld. In this case, there is a possibility that defects will occur at the joint with the previous weld when subsequent welding is performed after the tabs are removed.

The welding method that solves the above problem is a joining method for joining the joint between the upper and lower column members that make up a box column by welding, and includes a first step of placing a tab to stop the weld at a position beyond the corner line of the box column in the space that will become the joint, and performing pre-welding to weld the welding area on one side of the space, a second step of removing the tab and grinding the end of the pre-weld toward the line, and a third step of performing post-welding to join the end of the pre-weld.

The present invention makes it possible to manufacture box columns with good joints.

FIG. 13 is a perspective view showing an upper pillar member disposed on a lower pillar member in an embodiment. 4 is a flow chart illustrating the processing steps of a method for joining box columns in an embodiment. FIG. 13 is a perspective view showing a state in which a tab is disposed in a space that serves as a joint in the embodiment. FIG. 13 is a plan view showing a tab disposed in a space that serves as a joint in the embodiment. FIG. 13 is a plan view showing a state in which pre-welding is performed with the tab placed in the embodiment. FIG. 13 is a plan view of the embodiment after the end of the pre-weld has been ground off. FIG.

Below, one embodiment of a method for joining box columns will be explained using Figures 1 to 7. Here, the box column of this embodiment is constructed by stacking column members each made of four steel plates arranged to form a rectangular frame shape. In this case, the box column is constructed by fixing the joints of the stacked column members by welding. In the figures below, the dimensions of the plates that make up the box column, such as length, width, and thickness, have been altered to make them easier to understand.

In this embodiment, as shown in FIG. 1, first, the upper column member 12 is stacked on the lower column member 11 that constitutes the box column 10. Here, the lower column member 11 and the upper column member 12 have almost the same configuration. Specifically, the lower column member 11 (upper column member 12) has two short plate members T1 and two plate members T2 that are longer than the plate members T1. Then, the ends of the two separated short plate members T1 and the long plate member T2 are arranged facing each other at a certain distance (root gap), and the plate members T1 and T2 are fixed together by welding at the corner joint welded portion W1 to form the lower column member 11 (upper column member 12). Note that a backing metal 13 is arranged at the inner corner of each column member (11, 12) in correspondence with the root gap.

In addition, a groove portion 12g inclined at an angle of, for example, 35 degrees is formed at the lower end of the stacked upper pillar member 12. Backing metals 16 and 17 are arranged as backing members on the inside of each pillar member (11, 12) so that the lower pillar member 11 and the upper pillar member 12 are kept apart by a certain distance (root gap). The backing metals 16 and 17 are provided corresponding to the range of the preceding welding and the range of the following welding, respectively. In this embodiment, the backing metal 16 is longer than the backing metal 17 and is used for the preceding welding.
Furthermore, an erection piece (not shown) is provided on the plate member T2 of the lower column member 11 and the plate member T2 of the upper column member 12. The positions of the lower column member 11 and the upper column member 12 are aligned using these erection pieces.

(Method of welding box column 10)
Each step of the welding method for the box column 10 will be described with reference to FIG.
First, as shown in Fig. 3, a tab is placed in the joint area (step S1). Here, the tab 15 is disposed in the space (joint area) between the lower column member 11 and the upper column member 12 where the joint is to be provided.

In this case, as shown in FIG. 4, four tabs 15 are placed at positions shifted toward the plate member T2 at each corner of the joining area. Here, the four tabs 15 are placed at positions beyond the diagonal line L1 with respect to the first welding area G1 so that the first welding area G1 where the pre-welding is performed is expanded. Specifically, at each corner where the plate members T1 and T2 contact in the orthogonal direction of the lower pillar member 11 (upper pillar member 12), the tabs 15 are placed at positions on the plate member T2 side that are parallel to the diagonal line L1 and longer than the diagonal line L1 by the cutting allowance D1. Here, the diagonal line L1 is a line connecting the inner corner and the outer corner, and forms an angle of 45 degrees with respect to the extension direction of the plate members T1 and T2 that are orthogonal to each other. The cutting allowance D1 is, for example, about 5 mm. This cutting allowance D1 is a length that allows welding by moving back and forth from one tab 15 to another adjacent tab 15, so that the area surrounded by the tab 15 and the backing metal 16 can be welded without any voids.

Next, preliminary welding is performed (step S2). Specifically, straight rails are attached to the outer periphery of the plate member T1 of the upper pillar member 12 above the first welding area G1 so that they are parallel to the plate member T1. Then, a welding robot is attached to each rail. These two welding robots are configured by connecting a traveling cart and a welding torch connected to each rail with a base, and are equipped with a power cable, welding metal wire, etc. Then, the tip of the torch of each welding robot is positioned opposite the backing metal 16 in the first welding area G1 so as to face the groove portion 12g of the upper pillar member 12.

As shown in FIG. 5, the welding robots are then moved back and forth between adjacent tabs 15 in each first welding area G1 by automatic control, and welding passes are overlapped to perform welding. In this case, the two welding robots are positioned to move along opposing sides of the lower pillar member 11, and simultaneously weld the first welding area G1. After the preliminary welding is completed, the welding robots and rails are removed.

Next, as shown in FIG. 5, the tab 15 is removed from the first welding area G1 between the lower column member 11 and the upper column member 12 (step S3). At this time, the end of the pre-welded portion (pre-welded portion PW1) is in contact with one side of the tab 15 and is located on the plate member T2 side by the cutting allowance D1 from the diagonal line L1. After that, the erection piece is also removed.

6, the end of the previous weld PW1 is ground toward the diagonal line (step S4). Here, the end of the previous weld PW1 is ground down to the diagonal line L1 with a grinder or the like.
Next, post-welding is performed (step S5). Specifically, straight rails are attached to the outer periphery of the plate member T2 of the upper pillar member 12 above the second welding area G2 so as to be parallel to the plate member T2. Then, a welding robot having the above-mentioned configuration is attached to each rail. Then, the tip of the torch of each welding robot is positioned in the second welding area G2 so as to face the groove portion 12g of the upper pillar member 12 and to face the backing metal 17.

7, the welding robots are automatically moved back and forth between the ends of the cut preceding welds PW1 in each second welding area G2, and welding passes are overlapped to perform welding. In this case, the two welding robots are arranged to move along opposing sides of the lower pillar member 11, and simultaneously weld the second welding areas G2.
When the subsequent welding is completed, a subsequent welded portion TW1 is formed in the second welding region G2 between the plate members T1. Then, the welding robot and the rail are removed.
This completes the joining of the lower pillar member 11 and the upper pillar member 12. As a result, the lower pillar member 11 and the upper pillar member 12 are joined at a joint constituted by the preceding welded portion PW1 and the succeeding welded portion TW1 formed in the joining region.

(Action)
In this embodiment, the tabs 15 are offset and installed (step S1), and then the prior welding is performed (step S2). As a result, an excess portion is generated in the prior weld PW1, and the end of this excess portion is cut (step S4), and then the subsequent welding is performed (step S5). Therefore, by cutting, welding defects generated at the end of the prior welding can be removed, and then the subsequent welding can be performed.

According to this embodiment, the following effects can be obtained.
(1) In this embodiment, the tabs 15 are shifted and positioned in the joint area between the lower column member 11 and the upper column member 12, and then the pre-welding is performed (step S2). Then, the end of the pre-welding is scraped (step S4), and then the post-welding is performed to form an end to be joined to the scraped portion (step S5). As a result, defects such as cavities generated at the end of the pre-welding are scraped and reduced, and then the post-welding is performed on this end, so that the box column 10 in which the pre-welding and the post-welding are satisfactorily connected can be manufactured.

(2) In this embodiment, the tab 15 is positioned offset from the diagonal line L1 so that the area of the pre-weld is larger, and then pre-weld is performed (step S2), and the end of the pre-weld is ground toward the diagonal line (step S4). As a result, the end that has been welded more than the diagonal line L1 is ground, so that the end of the subsequent weld can be joined to the ground end of the pre-weld. In addition, since the end is ground to match the diagonal line L1, the seam is aligned with the diagonal line L1 connecting the inner corner and the outer corner, so a good appearance can be achieved. Furthermore, in this case, since the cutting is done parallel to the diagonal line L1, it is easy to grind with a grinder, etc.

(3) In this embodiment, the tab 15 is positioned offset from the diagonal line L1 by the cutting allowance D1. This cutting allowance D1 allows the area surrounded by the tab 15 and the backing metal 16 to be welded without any voids simply by moving the welding path back and forth across the two tabs 15.

(4) In this embodiment, the lower column member 11 and the upper column member 12 are aligned using the erection piece, and then the first welding area G1 between the plate members T1 where the erection piece is not provided is welded first. This allows the lower column member 11 and the upper column member 12 to be efficiently aligned and welded.

This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.
In the above embodiment, the tab 15 disposed in the joining region is shifted from the diagonal line L1 by the cutting allowance D1. The size of this cutting allowance D1 is not limited to about 5 mm as described above, as long as it is large enough to remove defects such as cavities that occur at the end. However, if the cutting allowance D1 is made large, welding to the backing metal 16 located in the cutting allowance cannot be performed sufficiently, and the cutting work takes time and effort, so it is preferable to make the cutting allowance D1 as small as possible.

- In the above embodiment, the end of the preceding weld PW1 is cut toward the 45-degree diagonal line L1 connecting the inner corner and the outer corner, up to the diagonal line L1. The end of the preceding weld PW1 to be cut is not limited to 45 degrees, and it is sufficient if it is cut into a straight line shape that allows the subsequent welding to connect well with the end of the preceding weld PW1. In this case, if it is cut toward the diagonal line L1, it is not necessary to cut exactly to the diagonal line L1, and it is sufficient to cut to the vicinity of the diagonal line L1.

- In the above embodiment, the first welding area G1 between the plate member T1 of the lower column member 11 and the plate member T1 of the upper column member 12 is pre-welded, and the second welding area G2 between the plate member T2 of the lower column member 11 and the plate member T2 of the upper column member 12 is welded later (post-welded). The locations of the pre-welding and post-welding may be reversed. In this case, the tab 15 is positioned shifted toward the plate member T1 side from the second welding area G2 between the plate members T2 for which pre-welding is performed.

- In the above embodiment, the rail and welding robot are positioned at the positions of the two opposing sides, and the two opposing sides are welded simultaneously. When welding with a welding robot, it is not necessary to weld the two opposing sides simultaneously, and welding can be done one side at a time in sequence.

Next, the technical ideas that can be understood from the above embodiment and other examples will be described below.
(a) the lines are diagonal lines connecting an inner corner and an outer corner of the box column,
2. The method of claim 1, wherein in the first step, the tabs are arranged parallel to the diagonal line.
(b) A method for welding a box column as described in claim 1 or (a), characterized in that the tab has a size such that the space formed between the tab and the backing member is filled by the welding performed by the prior welding.
(c) A method for welding a box column as described in (a) or (b) of claim 1, characterized in that the first step involves welding two opposing first joint areas, and the third step involves welding a second joint area perpendicular to the first joint areas.

D1...machining allowance, G1...first welding area, G2...second welding area, T1, T2...plate member, W1...corner joint weld, L1...diagonal line, PW1...preceding weld, TW1...subsequent weld, 10...box column, 11...lower column member, 12...upper column member, 12g...groove, 13, 16, 17...backing metal, 15...tab.

Claims (1)

A joining method for joining a joint between an upper column member and a lower column member that constitute a box column by welding,
A first step of performing pre-welding by placing a tab for stopping welding at a position beyond the corner line of the box column in the space to be the joint and welding a welding area on one side of the space;
a second step of removing the tab and grinding the end of the pre-weld toward the line;
and a third step of performing a subsequent welding to join the end of the preceding weld.